BERLIN — An Air Berlin flight from Namibia to Munich was delayed after police found a suspicious bag in the luggage hall of the airport in the southern African nation's capital, authorities said Thursday.

Germany sent federal police experts stationed in South Africa to help in the investigation amid heightened concerns of terrorist threats against Germany, though it appeared later that the bag may have been part of an airport security test.

Security officials told NBC News the piece of baggage did not contain a bomb or any explosives. They said it was a look-alike device, one commercially made explicitly for governments and airports to test their own security procedures.

The device was of the type that security professionals call a "Wile E. Coyote bomb," because of its somewhat-cartoonish appearance — batteries, a fuse and a clock, NBC reported.

The officials said it had no luggage routing tag or a shipping label, so it was apparently not intended to be placed on any plane.

"There are indications that it could be a test," German Interior Minister Thomas de Maiziere told broadcaster ZDF, adding that close expert scrutiny would soon reveal the true nature of the bag.

Teller said the airline had been told that no explosives were found in the bag but Namibia's Police Inspector General Sebastian Ndeitunga said the bag "needs to be tested in the lab to find out whether it was an explosive or just a decoy."

The bag was on its own, "wrapped in plastic without a tag," which raised suspicion, Ndeitunga said.

The incident came as Germany already was on edge after de Maiziere raised the country's terrorist threat level on Wednesday, saying intelligence services had received a tip from an unspecified country about a suspected attack planned for the end of November.

Concern about the possibility of international flights being targeted by terrorists rose last month when two mail bombs were discovered while being sent on cargo planes from Yemen to the U.S. One of them went through a German airport before being found in Britain.

After the suspect bag was found, the Air Berlin flight's luggage was rechecked as a precaution and all passengers on the flight had to identify their bags, and none was found without an owner, Teller said.

Teller said she did not know whether Namibian police had determined who owned the suspicious bag or what flight it was intended for. Namibian police said no arrests had been made.

The Namibia Airports Company indicated in a statement that the bag may have been intended as cargo on the plane.

The plane arrived safely with its almost 300 passengers in Munich early Thursday morning, Teller said.

The Associated Press and NBC's Pete Williams contributed to this report.

Video: Terror warning puts Germany on high alert

Transcript of: Terror warning puts Germany on high alert

BRIAN WILLIAMS, anchor:over the latest terrorism scare after a very suspicious package turned up at the main airport in
Namibia
in
Africa
apparently bound for
Munich
in
Germany
. And the
German people
have been warned of a possibly impending
terrorist attack
. Our own
Stephanie Gosk
has arrived in
Munich
tonight and has the latest on the investigation.
Stephanie
, good evening.

STEPHANIE GOSK reporting:Good evening,
Brian
. Well, US officials tell
NBC News
this was not a bomb. It was actually a commercially made fake complete with wires, batteries and the clock. It's the kind of thing that's normally used to test security procedures. What's unclear tonight is why it was found in
Namibia
alongside luggage about to board an
Air Berlin
flight to this airport here in
Munich
. This comes as German officials are saying that a
terrorist attack
in this country could be imminent. The interior minister raised the threat level here on Wednesday and said that the government has received specific, concrete information from an unspecified foreign intelligence group that there could be an attack in a major city in
Germany
this week. They've raised security in places like train stations and airports. We noticed it here in
Munich
. It's very clear this week,
Brian
, that German officials are worried this country could be the terrorists' next target.
Brian
: